The first freezing temperatures of the season are not only a sign for Northeasterners to dig their scarves and winter jackets out of the closet. It is also the time to get a flu vaccine, experts say.

"People should be getting vaccinated for the flu right now," said Dr. Diane Tenenbaum, a pediatrician at St. Peter's Hospital in Albany. "Now is the perfect time."

Although the flu season is just beginning and usually does not peak until February, Tenenbaum explained that cases of the flu begin increasing in late December and early January.

"It usually takes at least two weeks to develop some degree of immunity after getting the flu vaccine," she said, "so right now would be a great time to get the vaccine to protect yourself throughout the season."

"Although there is no confirmed flu in the vicinity, now is the time to get the vaccine," Sorum said. "I think we'll start getting some confirmed cases to the hospital in December."

Seasonal influenza, or the flu, is a contagious respiratory illness caused by a range of influenza viruses that tends to spread during the winter season. Although the viruses that cause the flu are well studied, the timing and duration of the flu season can be unpredictable.

"The flu season varies from year to year, so it's hard to say when the season will begin and end," Sorum explained.

"It is the $10,000 question," Tenenbaum said. "There are patterns to the flu that are tracked worldwide by the Centers for Disease Control, and the flu season is predicted based on that historical data."

"For example, we know that the flu happens a little bit earlier in the southern part of the United States, and it takes some time for it to spread to the Northeast," Tenenbaum explained.

No matter the time of year, most healthy individuals who get the flu can expect a fever, runny nose, chills and fatigue that go away within a week.

However, in "high-risk" individuals, including infants, the elderly and those with chronic diseases, the flu can cause life-threatening complications that require hospitalization.

"Although the scariest complication of the flu is death, we more commonly see pneumonia and dehydration, which require hospitalization," Tenenbaum said.

The elderly are particularly at risk, with the CDC reporting that 90 percent of influenza-associated deaths occur among adults over 65 years of age.

"The most at-risk are the very young and the very old and anybody whose immune system doesn't work so well, including those with asthma and chronic lung or cardiac diseases," said Tenenbaum. "These people should be consulting with the physicians about getting a flu shot."

However, it is equally important for healthy adults to be vaccinated for the flu, not only to protect themselves from getting sick, but also to protect others.

"You can't see if someone sitting next to you is immunocompromised," Tenenbaum said, "so you should get vaccinated to protect the community as well."

Sorum said this is a change from previous practices when only "high-risk" patients were encouraged to get the vaccine.

Otherwise healthy individuals should get a flu vaccine "first because, even though it's rare, the flu can cause severe illness, even in healthy people ... But, more importantly, to protect people who are less healthy by not spreading the flu to them," Sorum said.

This concept, known as "herd immunity," means that the flu vaccine affords double the protection -- protecting the vaccinated person and preventing them from passing the flu to anyone else.

"Protecting healthy people protects a lot of people," Tenenbaum said.

Flu vaccination is particularly important for families with babies who are younger than six months of age.

"Babies under 6 months of age are quite vulnerable and we can't protect them by giving them the vaccine," Tenenbaum said. "It is very important for families to be vaccinated so they don't spread the flu to babies."

Sorum said despite the benefits, many people avoid getting a flu shot because they fear the vaccine will give them the flu rather than protect them from it.

That's an unfounded fear, he said. "It is absolutely not possible to get the full flu from a flu vaccine. It is biologically impossible."

Sorum explained that with so many other illnesses going around in the winter months, there is a high probability that someone who receives the flu vaccine will get sick from another illness. He said that often leads people to wrongly connect the vaccination they received to the separate sickness they contracted.

The flu vaccine is available in an injection and a nasal spray, and may have side effects in certain individuals.

"There are complications and side effects to anything we're exposed to, and anyone getting the vaccine should speak with their physician," Tenenbaum said.

"Unless you have a severe -- and I mean severe -- allergy to eggs, unless you are currently having moderate to severe illness and unless you have had a bad reaction to the vaccine in the past, you should get the flu vaccine," Tenenbaum said. "You risk putting people you care about in the hospital if you don't."